The present invention relates to an improved visual aid system for assisting an operator while he is backing a truck, recreational vehicle, or other transporter into a given parking site and has particular applicability to transporters in which the rear of the transporter is blocked from the view of the operator while he is seated in the cab or other operator's station. More specifically, the invention involves the use of a closed circuit video system together with distance indicating means which visually shows to the operator the decreasing distance from the transporter to the rear end of the parking site as the transporter is being backed.
The operator of a truck or truck and trailer unit often experiences considerable difficulty in maneuvering the vehicle in reverse because he commonly cannot see directly to the rear thereof. Hence, the operator can be blind to objects on the road or to overhead obstructions and often experiences difficulty, without the aid of an assistant acting on foot as a spotter, to not only safely back the transporter, but to accurately maneuver it so that the rear of the transporter is squarely up to a loading dock. If a spotter is not available, the operator must either take his chances or get in and out of the vehicle several times to check his backing progress.
Safety and economic considerations have long dictated an alternative superior to the foregoing operator options, which would effectively take the blinders off the operator while backing and could be of rear view assistance to him while driving along a highway.
In the past some consideration has been given to the use of closed circuit television in vehicles. For example, British Pat. No. 934,037 discloses an articulated truck and trailer unit in which a television camera is arranged to view through a rear window in the trailer and a television monitor is mounted with its viewing screen in the dashboard of the truck. French Pat. Nos. 1,343,660 and 1,396,129 also disclose rear view television use on vehicles. British Pat. No. 1,155,807 discloses a rear observation closed circuit television system for automobiles in which there is a deflecting circuit switching arrangement adapted to switch the horizontal deflecting circuit of the television camera to reverse polarity so that when the camera is facing to the rear of the vehicle and the operator is facing forwardly while viewing the picture in the monitor, the operator will not see left and right in reverse compared with what he sees in a rear view mirror.
U.S. Pat. No. 3,689,695 discloses a vehicle viewing system in which a television camera is mounted above the top of the operator's truck cab and has a support designed to permit the camera to have vertical, horizontal, rotary, or tilting movement, or lateral movement across the width of the cab.
None of the foregoing prior patents discloses a system whereby the operator can accurately tell how close the backing vehicle is to a loading dock or other parking objective. The preferred embodiment of the present invention meets that long existing need. Another benefit is that the operator of a vehicle having limited rear vision cannot only see rearwardly approaching vehicles, but can judge how far they are behind.
In accordance with an embodiment of the present invention, a closed circuit television system utilizes distance indicating means having a readout at the operator's station. The distance indicating means can take various forms and involves the use of an on-site permanent or portable backing target or distance indicating indicia on the roadway. Various species of backing target and read-out means are used in different embodiments. For example, in one embodiment, a television monitor has a distance scale on its screen which is coordinated with the size of the backing target to indicate the inverse relationship between the distance from the vehicle to the target and the size of the target image appearing on the screen. This and other embodiments are detailed in the following description.